A cloud computing, which is internet-based computer technology, offers environments in which a user can use necessary software at any time through internet access without installing it in his or her computer and also easily share data by means of various information communication devices. Namely, an individual user can use a program such as Photoshop, Office, etc. by accessing a web and also store a resultant outcome in the web. Consequently, many users can work individually through a single server (i.e., a computer) disposed in a virtual space. An automated teller machine (ATM) of a bank and a real-time reservation system of aircraft or train are representative examples.
With the growth of information technology (IT), with the expansion of an application market, and with the activation of a social network service (SNS), data traffic such as users' contents is increasing explosively in these days. Additionally, excessive data traffic incurs an uncontrollable situation beyond each individual terminal's capacity. A cloud system is expected to solve favorably such an undesirable situation. Further, this cloud system will become the foundation for constructing a small-sized device environment.
For example, when a service or function that requires large-volume image processing is executed, this service or function may be executed at a server based on the cloud computing. Then the server transmits only a screen of execution result to a user terminal, using streaming technique. Therefore, the user can use, at his or her terminal, a service or function that requires higher specifications or higher functionality.
This technique to enable a user terminal to use various services or functions through image virtualization for executing a specific service or function in response to a request of the user terminal and then sending an execution result to the user terminal is referred to as a cloud streaming service.
In a computing environment based on this cloud streaming service, since main services or function are executed at a server, technique to detect in advance whether there is any failure in the server is required.